Simplify the following expression: $k = \dfrac{h - f}{3g} - \dfrac{6f - 2h}{3g}$ You can assume $f,g,h \neq 0$.
Solution: Since the expressions have the same denominator we simply combine the numerators: $k = \dfrac{h - f - (6f - 2h)}{3g}$ $k = \dfrac{3h - 7f}{3g}$